Interferometric diffuse optics: recent advances and future outlook

Zhou, Wenjun; Zhao, Mingjun; Srinivasan, Vivek J.

doi:10.1117/1.nph.10.1.013502

Cited by 9 publications

(6 citation statements)

References 67 publications

(174 reference statements)

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“…Although these separations are commonly used in the continuous wave DCS literature, it remains to be seen whether these results would hold true for different SDS combinations. With improvements in DCS hardware that enable larger SDS, 25 – 27 the utility of multilayered modeling should be re-evaluated, as the enhanced depth penetration of the second separation would likely improve model performance. Another limitation of this study is that it was not designed to determine which model is most accurate for use in human datasets.…”

Section: Discussionmentioning

confidence: 99%

Comparison of diffuse correlation spectroscopy analytical models for measuring cerebral blood flow in adults

Zhao,

Sathialingam,

Cowdrick

et al. 2023

J. Biomed. Opt.

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.SignificanceAlthough multilayer analytical models have been proposed to enhance brain sensitivity of diffuse correlation spectroscopy (DCS) measurements of cerebral blood flow, the traditional homogeneous model remains dominant in clinical applications. Rigorous in vivo comparison of these analytical models is lacking.AimWe compare the performance of different analytical models to estimate a cerebral blood flow index (CBFi) with DCS in adults.ApproachResting-state data were obtained on a cohort of 20 adult patients with subarachnoid hemorrhage. Data at 1 and 2.5 cm source-detector separations were analyzed with the homogenous, two-layer, and three-layer models to estimate scalp blood flow index and CBFi. The performance of each model was quantified via fitting convergence, fit stability, brain-to-scalp flow ratio (BSR), and correlation with transcranial Doppler ultrasound (TCD) measurements of cerebral blood flow velocity in the middle cerebral artery (MCA).ResultsThe homogeneous model has the highest pass rate (100%), lowest coefficient of variation (CV) at rest (median [IQR] at 1 Hz of 0.18 [0.13, 0.22]), and most significant correlation with MCA blood flow velocities (Rs = 0.59, p = 0.010) compared with both the two- and three-layer models. The multilayer model pass rate was significantly correlated with extracerebral layer thicknesses. Discarding datasets with non-physiological BSRs increased the correlation between DCS measured CBFi and TCD measured MCA velocities for all models.ConclusionsWe found that the homogeneous model has the highest pass rate, lowest CV at rest, and most significant correlation with MCA blood flow velocities. Results from the multilayer models should be taken with caution because they suffer from lower pass rates and higher coefficients of variation at rest and can converge to non-physiological values for CBFi. Future work is needed to validate these models in vivo, and novel approaches are merited to improve the performance of the multimodel models.

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Section: Discussionmentioning

confidence: 99%

Comparison of diffuse correlation spectroscopy analytical models for measuring cerebral blood flow in adults

Zhao,

Sathialingam,

Cowdrick

et al. 2023

J. Biomed. Opt.

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“…For SCOS, the implementation model was based on 850 nm operation with a CMOS camera with pixel number, read noise, and quantum efficiency properties based on aggregated camera properties for commercially available cameras 35 . Although great success has recently been shown in the application of interferometric methods to both SCOS and DCS, 14 , 15 , 36 – 41 we restricted the analysis in this work to strictly homodyne methods. The photon flux at each simulated source–detector separation was estimated from the diffuse reflectance output from MMC and scaling the results based on estimates from previous studies 42 .…”

Section: Methodsmentioning

confidence: 99%

Comparing the performance potential of speckle contrast optical spectroscopy and diffuse correlation spectroscopy for cerebral blood flow monitoring using Monte Carlo simulations in realistic head geometries

Robinson,

Cheng,

Renna

et al. 2024

Neurophoton.

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The non-invasive measurement of cerebral blood flow based on diffuse optical techniques has seen increased interest as a research tool for cerebral perfusion monitoring in critical care and functional brain imaging. Diffuse correlation spectroscopy (DCS) and speckle contrast optical spectroscopy (SCOS) are two such techniques that measure complementary aspects of the fluctuating intensity signal, with DCS quantifying the temporal fluctuations of the signal and SCOS quantifying the spatial blurring of a speckle pattern. With the increasing interest in the use of these techniques, a thorough comparison would inform new adopters of the benefits of each technique.Aim: We systematically evaluate the performance of DCS and SCOS for the measurement of cerebral blood flow.Approach: Monte Carlo simulations of dynamic light scattering in an MRI-derived head model were performed. For both DCS and SCOS, estimates of sensitivity to cerebral blood flow changes, coefficient of variation of the measured blood flow, and the contrast-to-noise ratio of the measurement to the cerebral perfusion signal were calculated. By varying complementary aspects of data collection between the two methods, we investigated the performance benefits of different measurement strategies, including altering the number of modes per optical detector, the integration time/fitting time of the speckle measurement, and the laser source delivery strategy.Results: Through comparison across these metrics with simulated detectors having realistic noise properties, we determine several guiding principles for the optimization of these techniques and report the performance comparison between the two over a range of measurement properties and tissue geometries. We find that SCOS outperforms DCS in terms of contrast-to-noise ratio for the cerebral blood flow signal in the ideal case simulated here but note that SCOS requires careful experimental calibrations to ensure accurate measurements of cerebral blood flow. Conclusion:We provide design principles by which to evaluate the development of DCS and SCOS systems for their use in the measurement of cerebral blood flow.

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“…The interested reader is referred to [84] for an excellent and fuller treatment of the recent work in the nascent area of interferometric DCS techniques.…”

Section: Interferometric Approachesmentioning

confidence: 99%

Diffuse Correlation Spectroscopy: A Review of Recent Advances in Parallelisation and Depth Discrimination Techniques

James,

Munro

2023

Sensors

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Diffuse correlation spectroscopy is a non-invasive optical modality used to measure cerebral blood flow in real time, and it has important potential applications in clinical monitoring and neuroscience. As such, many research groups have recently been investigating methods to improve the signal-to-noise ratio, imaging depth, and spatial resolution of diffuse correlation spectroscopy. Such methods have included multispeckle, long wavelength, interferometric, depth discrimination, time-of-flight resolution, and acousto-optic detection strategies. In this review, we exhaustively appraise this plethora of recent advances, which can be used to assess limitations and guide innovation for future implementations of diffuse correlation spectroscopy that will harness technological improvements in the years to come.

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Interferometric diffuse optics: recent advances and future outlook

Cited by 9 publications

References 67 publications

Comparison of diffuse correlation spectroscopy analytical models for measuring cerebral blood flow in adults

Comparison of diffuse correlation spectroscopy analytical models for measuring cerebral blood flow in adults

Comparing the performance potential of speckle contrast optical spectroscopy and diffuse correlation spectroscopy for cerebral blood flow monitoring using Monte Carlo simulations in realistic head geometries

Diffuse Correlation Spectroscopy: A Review of Recent Advances in Parallelisation and Depth Discrimination Techniques

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